New surveillance video from Istanbul appears to show a Saudi agent wearing journalist Jamal Khashoggi's clothing and leaving Riyadh's consulate on October 2, presumably in an attempt to cover up his killing by showing he had left the diplomatic outpost alive.

The video was taken by Turkish law enforcement and shown Monday on CNN, suggesting Saudi agents used a body double in an effort to conceal the murder.

The video surfaced as Saudi officials offered yet another explanation for the death of the 59-year-old Saudi journalist who had been living in the U.S. in self-imposed exile while he wrote columns for The Washington Post that were critical of Saudi Crown Prince Mohammed bin Salman and Riyadh's involvement in the conflict in Yemen.

The Saudis at first said Khashoggi had left the consulate and that they did not know his whereabouts. They then said he died in a fist fight after an argument inside the consulate. Now they say he died in a chokehold to prevent him from leaving the consulate to call for help.

A still image taken from CCTV video and obtained by TRT World claims to show Saudi journalist Jamal Khashoggi, highlighted in a red circle by the source, as he arrives at Saudi Arabia's Consulate in Istanbul, Turkey, Oct. 2, 2018.

It is not known what happened to Khashoggi's remains, although Turkish officials say he was tortured, decapitated and then dismembered. One Saudi official told ABC News Khashoggi's body was given to a 'local cooperator' in Istanbul for disposal, but Saudi officials have said they do not know what happened to his remains.

Saudi Arabia said Mohammed spoke Monday by telephone with Khashoggi's son to express condolences for the killing.

Turkish President Recep Tayyip Erdogan is vowing to reveal details about the case in a Tuesday speech to his parliament.

He told an Istanbul rally Sunday, 'We are looking for justice here and this will be revealed in all its naked truth, not through some ordinary steps.'

Erdogan spoke to U.S. President Donald Trump by telephone Sunday. Turkey's state-run news agency said both leaders agree the Khashoggi case needs to be 'cleared up with all aspects.'

Saudi Foreign Minister Adel al-Jubeir told Fox News Sunday Khashoggi's killing inside its Istanbul consulate was 'a huge and grave mistake' and vowed those responsible for it would be held accountable.

He said Saudi agents 'did this out of the scope of their authority,' calling it 'a rogue operation.'

The top Saudi diplomat offered his condolences to Khashoggi's family, but disclosed no new information about how the writer was killed or where his body is. At the same time, he denied that the crown prince - the country's de facto ruler - was involved.

'There obviously was a tremendous mistake made and what compounded the mistake was the attempt to try to cover up,' al-Jubeir said. 'That is unacceptable in any government.'

International scorn

Saudi Arabia claims that Khashoggi was killed after an argument leading to a fist fight has drawn widespread international scorn and skepticism, including from Trump. After he initially seemed willing to believe Saudi accounts, the president now says 'obviously there has been deception, and there has been lies.'

'This is an aberration,' al-Jubeir said in the Fox television interview. 'This is a mistake and those responsible will be punished for it. 'We want to make sure that we know what happened and we want to make sure that those responsible be held to account.'

Saudi Arabia says it has fired five key officials linked to the death and arrested 18 others.

Royal sanction?

Critics are questioning how a team of 15 Saudi agents could fly to Istanbul to meet Khashoggi and eventually kill him without the crown prince's knowledge and consent. But al-Jubeir said these 'were not people closely tied to him,' although news accounts have said that several Saudi security officials close to Mohammed were involved.

'Incredible ally'

Even as Trump criticized Saudi Arabia's fist-fight explanation for Khashoggi's death, he told the Post Riyadh has been an 'incredible ally' of the United States for decades and it is possible the crown prince did not order Saudi agents to kill Khashoggi.

'Nobody has told me he is responsible. Nobody has told me he is not responsible,' the U.S. leader said. 'We have not reached that point. ... I would love if he was not responsible.'

Numerous U.S. lawmakers, including Trump's Republican colleagues, are calling for sanctions against the Saudis.

Trump told the Post that 'something will take place' in response to Khashoggi's death, but said the United States should not let the incident disrupt a possible $110 billion weapons sale to Riyadh he announced last year.